The wreckage of a British F-35B stealth jet that crashed into the Mediterranean Sea earlier this month has been located by experts, but not yet recovered from the ocean, the UK's National Security Adviser understands.
Speaking to the Commons Defence Select Committee, Sir Stephen Lovegrove said: "Clearly the swift recovery of the aircraft is what we would like to do, and we are working closely with allies on the mechanics of that, but I can't go into too much detail about it for reasons of operational security.
"We haven't got the plane up yet; an investigation is certainly ongoing into the incident."
Watch: Is this the moment a British F-35B crashed?
The former Permanent Secretary to the Ministry of Defence added: "My understanding is that the experts know where the aircraft is."
A joint UK-US operation was launched to retrieve the wreck.
The Lightning jet's pilot, who safely ejected from their aircraft, was able to return to the Queen Elizabeth-class aircraft carrier.
The Ministry of Defence (MOD) says it is "aware" of a video shared online, which appears to show the moment the aircraft crashed.
Sir Stephen told MPs it would be "premature of me to comment on what the reasons for the accident are".
He added: "The recovery of the flight data recorder and the wreckage are really vital for an accurate investigation to determine the causes of the crash."
When asked about whether he was concerned about the potential for Russian forces to be in the area and also looking for the wreckage, Sir Stephen replied: "We are aware of Russian undersea capabilities.
"The kinds of precautions and operations that we are undertaking at the moment are designed at least in part to ensure that the technology of the F-35 remains as confidential as you would like it to be.
"Those security aspects are very much at the top of our mind."